Brake light not working

Hi,

Having issues which is more than a simple bulb change, my brake left light has stopped working I change to a new bulb and still didn’t work.

I then thought it was the light panel I then plug the left light panel to the right and all lights were working and when I change the right light panel to the left the brake light was not working.

Could it be a wiring issue or a fuse?

Since I bought the car 3 years ago I had this issue before where left brake light stops working for a journey and then it starts working again.

Audi A4 B8 2013